U.S. patent number 10,150,831 [Application Number 15/654,782] was granted by the patent office on 2018-12-11 for acrylic processing aid and vinyl chloride resin composition comprising the same.
This patent grant is currently assigned to LG Chem, Ltd.. The grantee listed for this patent is LG Chem, Ltd.. Invention is credited to Geon Soo Kim, Yoon Ho Kim, Kwang Jin Lee.
United States Patent |
10,150,831 |
Lee , et al. |
December 11, 2018 |
Acrylic processing aid and vinyl chloride resin composition
comprising the same
Abstract
The present disclosure relates to an acrylic processing aid and
a vinyl chloride resin composition including the same, and in
particular, to a core-shell-structured acrylic processing aid
preparing a core using a silicone-azo macroinitiator and preparing
a shell using C12 to C18 alkyl methacrylate as a co-monomer, and a
vinyl chloride resin composition including the same. The acrylic
processing aid is used for sheet forming of the vinyl chloride
resin, and facilitates manufacture of a high-quality vinyl chloride
resin formed article having excellent transparency, adhesion
resistance and heat stability, having no non-dispersed melt
(fish-eye) production, and having significantly reduced air mark
and flow mark occurrences.
Inventors: |
Lee; Kwang Jin (Daejeon,
KR), Kim; Geon Soo (Daejeon, KR), Kim; Yoon
Ho (Daejeon, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG Chem, Ltd. |
Seoul |
N/A |
KR |
|
|
Assignee: |
LG Chem, Ltd.
(KR)
|
Family
ID: |
61158596 |
Appl.
No.: |
15/654,782 |
Filed: |
July 20, 2017 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20180044460 A1 |
Feb 15, 2018 |
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Foreign Application Priority Data
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Aug 9, 2016 [KR] |
|
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10-2016-0101091 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01J
13/14 (20130101); C08L 27/06 (20130101); C08F
297/00 (20130101); C08F 287/00 (20130101); C08L
27/06 (20130101); C08L 51/085 (20130101); C08L
27/06 (20130101); C08L 53/00 (20130101); C08L
2205/06 (20130101); C08L 2207/53 (20130101) |
Current International
Class: |
C08F
287/00 (20060101); B01J 13/14 (20060101); C08L
27/06 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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105504582 |
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2003025511 |
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2004359857 |
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JP |
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20010013109 |
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20040020963 |
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Mar 2004 |
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KR |
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KR |
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20060127730 |
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KR |
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100752503 |
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Aug 2007 |
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KR |
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101189384 |
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KR |
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Other References
Sahar Amiri, et al., "Silicone Macroinitiator in the Atom Transfer
Radical Polymerization of Styrene and Vinyl Acetate: Synthesis and
Characterization of Novel Thermoreversible Block Copolymers" ACS
Symposium Series, vol. 1154, Chapter 7, pp. 87-101 Publication Date
(Web): Dec. 10, 2013. cited by applicant.
|
Primary Examiner: Kaucher; Mark S
Attorney, Agent or Firm: Lerner, David, Littenberg, Krumholz
& Mentlik, LLP
Claims
What is claimed is:
1. An acrylic processing aid comprising: a core including an
acrylic-silicone block copolymer formed by copolymerizing methyl
methacrylate and a silicone-azo macroinitiator represented by the
following Chemical Formula 1; and a shell formed by copolymerizing
methyl methacrylate and a C12 to C18 alkyl methacrylate monomer:
##STR00003## wherein, in Chemical Formula 1, x is from 50 to 100
and n is from 1 to 10.
2. The acrylic processing aid of claim 1, wherein the silicone-azo
macroinitiator has a weight average molecular weight of 4,000 g/mol
to 80,000 g/mol.
3. The acrylic processing aid of claim 1, wherein the core
comprises the methyl methacrylate in 50% by weight to 90% by weight
and the silicone-azo macroinitiator in 0.01% by weight to 20% by
weight with respect to a sum of 100% by weight of the core monomers
in the copolymerization.
4. The acrylic processing aid of claim 1, wherein the core further
comprises a C2 to C18 alkyl acrylate monomer in 0% by weight to 30%
by weight with respect to a sum of 100% by weight of the core
monomers in the copolymerization.
5. The acrylic processing aid of claim 4, wherein the C2 to C18
alkyl acrylate monomer is one or more types selected from the group
consisting of ethyl acrylate, propyl acrylate, butyl acrylate, and
2-ethylhexyl acrylate and stearyl acrylate.
6. The acrylic processing aid of claim 1, wherein, in the shell,
50% by weight to 80% by weight of the methyl methacrylate and 20%
by weight to 50% by weight of the C12 to C18 alkyl methacrylate
monomer are copolymerized with respect to a sum of 100% by weight
of the shell monomers.
7. The acrylic processing aid of claim 1, wherein the C12 to C18
alkyl methacrylate monomer is one or more types selected from the
group consisting of lauryl methacrylate, cetyl methacrylate,
stearyl methacrylate, isostearyl methacrylate and tridecyl
methacrylate.
8. The acrylic processing aid of claim 1, wherein the shell further
comprises an aromatic vinyl monomer in 0% by weight to 30% by
weight with respect to a sum of 100% by weight of the shell
monomers in the copolymerization.
9. The acrylic processing aid of claim 8, wherein the aromatic
vinyl monomer is one or more types selected from the group
consisting of styrene, .alpha.-methylstyrene, o-ethylstyrene,
p-ethylstyrene and vinyl toluene.
10. The acrylic processing aid of claim 1, wherein the
acrylic-silicone block copolymer has specific viscosity of 0.3 to
2.0, wherein the specific viscosity is measured by dissolving 0.5 g
of the core in 10 ml of tetrahydrofuran (THF) solvent and by
calculating based on the following Mathematical Formula 1:
[Mathematical Formula 1] Specific viscosity=(time solution-time
THF)/time THF.
11. The acrylic processing aid of claim 1, which has specific
viscosity of 0.3 to 2.0, wherein the specific viscosity is measured
by dissolving 0.5 g of the acrylic processing aid in 10 ml of a
tetrahydrofuran (THF) solvent and by calculating based on the
following Mathematical Formula 1: [Mathematical Formula 1] Specific
viscosity=(time solution-time THF)/time THF.
12. The acrylic processing aid of claim 1 comprising: the core in
50% by weight to 80% by weight; and the shell in 20% by weight to
50% by weight.
13. A vinyl chloride resin composition comprising the acrylic
processing aid of claim 1.
Description
This application claims the benefit of Korean Application No.
10-2016-0101091 filed on Aug. 9, 2016, all of which are herein
incorporated by reference in their entirety.
FIELD OF THE INVENTION
The present disclosure relates to an acrylic processing aid
facilitating manufacture of a formed article having excellent
transparency, adhesion resistance and surface state and a vinyl
chloride resin composition including the same.
BACKGROUND OF THE INVENTION
A vinyl chloride resin is either a homopolymer of vinyl chloride or
a copolymer including 50% or more of vinyl chloride. The vinyl
chloride resin is widely used as a material of various products
including wires, electromechanical products, toys, films, sheets,
artificial leather, tarpauline, tapes, food packing materials and
medical supplies using foaming, extrusion, injection, calendering
and the like.
However, the vinyl chloride resin has a processing temperature
closer to a pyrolysis temperature, and therefore, has disadvantages
of having a narrow formable temperature range, having high melting
viscosity and having low fluidity. In addition, the vinyl chloride
resin tends to adhere to a metal surface of processing instruments
during high temperature processing, which frequently produces
carbides, and as a result, various problems relating to processing
such as quality decline of final formed articles occur. In view of
the above, a processing aid and a lubricant are used for enhancing
processing characteristics of the vinyl chloride resin.
A processing aid and a lubricant are additives improving melting
delay characteristics of the vinyl chloride resin itself and
thereby helping the vinyl chloride resin sufficiently exhibit
various mechanical and chemical properties, and have been
mandatorily used in processing of the vinyl chloride resin.
Specifically, Korean Patent Application Laid-Open Publication No.
2006-127730 proposed a method of reducing adhesion with metals by
adding a multilayer-structured polymer lubricant including
high-priced silicone-based latex, however, the method caused a new
problem of poor processing due to the silicon.
In addition, Korean Patent Application Laid-Open Publication No.
2004-0047510 disclosed a use of a core-shell-structured acrylic
processing aid, however, the use was not able to sufficiently
reduce adhesion with metals as well, and was not able to resolve a
problem of quality decline of final formed articles.
Particularly, a surface defect problem such as air marks, flow
marks and fish eyes having various shapes appearing on the surface
seriously occurred as well as the above-mentioned problems during
calender forming for sheet processing of the vinyl chloride
resin.
A method of adding a processing aid and a lubricant in large
quantities has been proposed in view of the above, however, a new
problem of transparency decrease has been caused.
Accordingly, means to reduce adhesion with metals and resolve a
surface defect problem while maintaining transparency has been
required, and such demands are very urgent considering the amount
of the vinyl chloride resin used throughout the industry.
PRIOR ART DOCUMENTS
Patent Documents
Korean Patent Application Laid-Open Publication No. 2006-127730
(2006 Dec. 13), Polymeric Lubricant Having Multilayer Structure and
Manufacturing Method Thereof
Korean Patent Application Laid-Open Publication No. 2004-0047510
(2004 Jun. 5), Copolymer Composition for Processing Aid
SUMMARY OF THE INVENTION
The inventors of the present disclosure have conducted studies from
various angles and, as a result, have identified that, when
preparing a core-shell-structured acrylic processing aid
copolymerized in a specific composition and adding this in
processing of a vinyl chloride resin, a surface defect problem such
as air marks, flow marks and fish eyes may be resolved while
maintaining transparency and while increasing adhesion resistance
and heat stability.
In view of the above, the present disclosure is directed to
providing an acrylic processing aid enhancing adhesion resistance
and heat stability of a vinyl chloride resin and having no surface
defect occurrences.
The present disclosure is also directed to providing a vinyl
chloride resin composition including the acrylic processing
aid.
One embodiment of the present disclosure provides an acrylic
processing aid including a core including an acrylic-silicone block
copolymer copolymerizing methyl methacrylate and a silicone-azo
macroinitiator represented by the following Chemical Formula 1; and
a shell copolymerizing methyl methacrylate and a C12 to C18 alkyl
methacrylate monomer:
##STR00001##
(In Chemical Formula 1, x is from 50 to 100, and n is from 1 to
10.)
Another embodiment of the present disclosure provides a vinyl
chloride resin composition including the acrylic processing
aid.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Hereinafter, the present disclosure will be described in more
detail.
Processing Aid
An acrylic processing aid capable of increasing adhesion resistance
without inhibiting transparency in a forming process of a vinyl
chloride resin, particularly, capable of suppressing surface
quality defects (air marks, flow marks, fish eyes) after a calender
forming process is provided.
The acrylic processing aid provided in the present disclosure has a
core-shell structure, and herein, specific initiator and monomer
are used as compositions of the core and the shell. Specifically, a
silicone-azo macroinitiator is used when preparing the core to
increase adhesion resistance and heat stability while maintaining
transparency, and a C12 or higher methacrylate co-monomer is used
when preparing the shell to suppress fish eyes formation, and
particularly, by controlling specific viscosity (.eta..sub.sp) of
the core and the processing aid, a role as a processing aid may be
performed together with suppressing air mark and flow mark
occurrences.
Specifically, the core of the acrylic processing aid comprises an
acrylic-silicone block copolymer prepared by copolymerizing methyl
methacrylate and a silicone-azo macroinitiator for increasing
adhesion resistance and heat stability.
Methyl methacrylate is a monomer that becomes a base composition of
the acrylic processing aid and performs a main role as a processing
aid. The methyl methacrylate is used in 50% by weight to 90% by
weight and preferably in 65% by weight to 85% by weight with
respect to a sum of 100% by weight of all the monomers forming the
core. When the content is less than the above-mentioned range, the
role as a processing aid, enhancing forming processability, may not
be obtained, and when the content is greater than the
above-mentioned range, the content of other monomers relatively
decreases, and a target level of properties aimed in the present
disclosure may not be obtained.
Particularly, the core of the acrylic processing aid according to
the present disclosure performs a polymerization reaction using a
silicone-azo macroinitiator represented by the following Chemical
Formula 1, and herein, the initiator copolymerizes with the methyl
methacrylate provided above to form an acrylic-silicone block
copolymer.
##STR00002##
(In Chemical Formula 1, x is from 50 to 100, and n is from 1 to
10.)
In the silicone-azo macroinitiator of Chemical Formula 1, the azo
group (--CN.dbd.NC--) is readily decomposed by heating or light
irradiation and performs a role of a polymerization initiator
generating radicals. The radicals of the azo group react with the
vinyl group included in the methyl methacrylate to form the
acrylic-silicone block copolymer repeatedly including a
dimethylsilicon group (Si(CH.sub.3).sub.2--O) and a dimethylsilane
group (Si(CH.sub.3).sub.2--CH.sub.2) of Chemical Formula 1. Herein,
by including a long molecular chain of a silicon group, the
acrylic-silicone block copolymer resolves a surface defect problem
such as flow marks and air marks produced in a formed article
surface, and performs a role of increasing heat stability as well
as reducing adhesion, due to a slip property of the silicon
itself.
In order to stably obtain adhesion resistance and heat stability, a
molecular weight and a content ratio of the silicone-azo
macroinitiator are controlled.
Specifically, the silicone-azo macroinitiator of Chemical Formula 1
has a weight average molecular weight of 4,000 g/mol to 80,000
g/mol and preferably 8,000 g/mol to 50,000 g/mol. When the provided
molecular weight is outside the above-mentioned range, functions as
the acrylic processing aid may not be fulfilled causing a problem
of declining processability and surface properties of a vinyl
chloride resin through overall property decline, and therefore, the
silicone-azo macroinitiator is properly selected and used so as to
satisfy the above-mentioned range.
As for the content, the silicone-azo macroinitiator is used in
0.01% by weight to 20% by weight and preferably in 5% by weight to
15% by weight with respect to a sum of 100% by weight of all the
monomers forming the core. When the content is less than the
above-mentioned range, enhancement in the adhesion resistance and
the heat stability of a vinyl chloride resin may not be expected,
and when the content is greater than the above-mentioned range,
transparency may decrease, and therefore, the silicone-azo
macroinitiator is properly used in the above-mentioned range.
Additionally, the core may be copolymerized further including a C2
to C18 alkyl acrylate monomer.
The C2 to C18 alkyl acrylate monomer performs a role of increasing
heat stability and transparency by increasing compatibility with a
vinyl chloride resin due to the presence of a hydrophobic group.
Specific examples thereof may comprise one or more types selected
from the group consisting of ethyl acrylate, propyl acrylate,
isopropyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl
acrylate and stearyl acrylate, and butyl acrylate is used in the
examples of the present disclosure.
The C2 to C8 alkyl acrylate monomer is used in 0% by weight to 30%
by weight and preferably in 1% by weight to 15% by weight with
respect to a sum of 100% by weight of all the monomers forming the
core. When the content is greater than the above-mentioned range,
compatibility with a vinyl chloride resin decreases and sufficient
processability is not obtained causing concern of producing air
marks and/or flow marks, and therefore, the C2 to C8 alkyl acrylate
monomer is properly used in the above-mentioned range.
In addition, the shell of the acrylic processing aid according to
the present disclosure is for providing a function as a processing
aid, that is, providing excellent surface characteristics, and is
prepared through copolymerizing methyl methacrylate and a C12 to
C18 alkyl methacrylate monomer.
The methyl methacrylate is for accomplishing base properties as a
processing aid, and is used in 50% by weight to 80% by weight and
preferably in 60% by weight to 75% by weight with respect to a sum
of 100% by weight of all the monomers forming the shell. When the
content is less than the above-mentioned range, the role as a
processing aid, enhancing forming processability, may not be
obtained, and when the content is greater than the above-mentioned
range, the content of other monomers relatively decreases, and a
target level of properties aimed in the present disclosure may not
be obtained.
Particularly, the acrylic processing aid of the present disclosure
uses a C12 to C18 alkyl methacrylate monomer as a co-monomer of the
methyl methacrylate.
The C12 to C18 alkyl methacrylate monomer may be one or more types
selected from the group consisting of lauryl methacrylate, cetyl
methacrylate, stearyl methacrylate, isostearyl methacrylate and
tridecyl methacrylate, and preferably, cetyl methacrylate and/or
stearyl methacrylate are used.
The content of such an alkyl methacrylate monomer affects adhesion,
heat stability and surface characteristics of a vinyl chloride
resin, and is from 20% by weight to 50% by weight and preferably
from 25% by weight to 40% by weight with respect to a sum of 100%
by weight of all the monomers forming the shell. When the content
is less than the above-mentioned range, adhesion resistance and
heat stability decrease, and flow marks, air marks and fish eyes
are produced on a formed article surface, which declines surface
qualities.
In addition, the shell further comprises an aromatic vinyl
monomer.
The aromatic vinyl monomer may enhance transparency and increase
heat stability of a vinyl chloride resin due to a high refractive
index. Specific examples thereof may comprise one type selected
from the group consisting of styrene, .alpha.-methylstyrene,
o-ethylstyrene, p-ethylstyrene, vinyl toluene and combinations
thereof. The aromatic vinyl monomer may be used in one, two or more
types, and preferably, styrene is used.
The aromatic vinyl monomer is used in 0% by weight to 30% by weight
and preferably in 1% by weight to 10% by weight with respect to a
sum of 100% by weight of all the monomers forming the shell. When
the content is greater than the above-mentioned range, viscosity of
the acrylic processing aid is not readily controlled due to an
increase in the molecular weight, and therefore, the content is
properly controlled within the above-mentioned range.
Meanwhile, the core-shell-structured acrylic processing aid
according to the present disclosure has the core and the processing
aid have specific viscosity as well as limiting the
composition.
Specific viscosity (.eta..sub.sp) is one way of expressing polymer
viscosity, and means a value obtained by dividing a value
subtracting a pure solvent flow time (t.sub.0) from a polymer
solution flow time (t) by the pure solvent flow time (t.sub.0) for
measuring polymer viscosity in a solution state.
.eta..times..times..times..times..times..times. ##EQU00001##
(In Mathematical Formula 1, t is a polymer solution flow time, and
to is a pure solvent flow time.)
Herein, having high specific viscosity is lengthening a flow time
and means having a high polymer molecular weight, and having low
specific viscosity is shortening a flow time and means having a low
polymer molecular weight.
In the present disclosure, the core is prepared to have a specific
viscosity range of 0.3 to 2.0 and preferably 0.5 to 1.8, and the
final processing aid having the shell formed therein as well is
prepared to have a specific viscosity range of 0.3 to 2.0 and
preferably 0.5 to 1.8. When specific viscosity of the core and the
processing aid is less than the above-mentioned range,
processability declines producing air marks on a formed article
surface, and when the specific viscosity is greater than the
above-mentioned range, flow marks are produced on a formed article.
In other words, when the specific viscosity is outside the
above-mentioned range, a problem such as surface property defects
occurs in a finally manufactured formed article, and therefore, the
specific viscosity is controlled to be in the above-mentioned
range.
Moreover, the core-shell-structured acrylic processing aid
according to the present disclosure comprises the core in 50% by
weight to 80% by weight and the shell in 20% by weight to 50% by
weight with respect to 100% by weight of all the monomers of the
core and the shell. Such a range may secure the effects described
above required for each of the core and the shell, that is, the
effects of enhancing adhesion resistance and heat stability without
decreasing transparency, and not producing air marks, flow marks
and fish eyes.
Method for Preparing Processing Aid
The preparation of the monomer-copolymerized processing aid
described above is not particularly limited, and may be prepared
through 2-step polymerization.
Specifically, the core-shell-structured acrylic processing aid is
prepared including preparing a core by copolymerizing, as monomers,
methyl methacrylate, a C2 to C18 alkyl acrylate monomer and a
silicone-azo macroinitiator; and
preparing a shell by mixing methyl methacrylate, a C12 to C18 alkyl
methacrylate monomer and an aromatic vinyl monomer to the core and
polymerizing the result.
Hereinafter, each step will be described.
First, a core is prepared by copolymerizing, as monomers, methyl
methacrylate, a C2 to C18 alkyl acrylate monomer and a silicone-azo
macroinitiator.
Herein, the copolymerization may be carried out using various
methods such as emulsion polymerization, mass-polymerization,
suspension polymerization and solution polymerization, and
preferably, emulsion polymerization is used.
Various compositions and reaction conditions of the initiator
required for the emulsion polymerization are not particularly
limited in the present disclosure, and follow those known in the
art.
As the initiator, a water-soluble initiator may be used, and
examples thereof may comprise inorganic peroxides such as sodium
persulfate, potassium persulfate, ammonium persulfate, potassium
superphosphate and hydrogen peroxide; organic peroxides such as
t-butyl peroxide, cumene hydroperoxide, p-menthane hydroperoxide,
di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide,
isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide,
3,5,5-trimethylhexanol peroxide and t-butyl peroxyisobutyrate;
nitrogen compounds such as azobisisobutyronitrile,
azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile and
azobisiso(butyric acid)methyl, and the like. These initiators are
used in 0.03 parts by weight to 0.2 parts by weight with respect to
100 parts by weight of all the monomers.
The polymerization may be carried out for 2 hours to 12 hours at
40.degree. C. to 80.degree. C.
According to one embodiment of the present disclosure, additives
commonly known in the art such as a redox catalyst, a
polymerization initiator, an emulsifier (or surfactant), a
molecular weight modifier, an activator and deionized water may be
further comprised in the emulsion polymerization.
As the emulsifier, one or more types may be selected from the group
consisting of anionic emulsifiers, cationic emulsifiers and
non-ionic emulsifiers, and the emulsifier is not particularly
limited in the present disclosure. As one example of the
emulsifier, one or more types may be selected from the group
consisting of anionic emulsifiers generally widely used in emulsion
polymerization such as sulfonate-based, carboxylate-based,
succinate-based, sulfosuccinate and metal salts thereof, for
example, alkylbenzene sulfonate, sodium alkylbenzene sulfonate,
alkyl sulfonate, sodium alkyl sulfonate, sodium polyoxyethylene
nonyl phenyl ether sulfonate, sodium stearate, sodium dodecyl
sulfate, sodium lauryl sulfate, sodium dodecyl sulfosuccinate and
abietate; cationic emulsifiers in which amine halides, alkyl
quaternary ammoniums, alkyl pyridinium salts and the like bond as a
functional group of higher aliphatic hydrocarbon; and non-ionic
emulsifiers such as polyvinyl alcohol and polyoxyethylene nonyl
phenyl, however, the emulsifier is not limited to these
emulsifiers. Such an emulsifier may be used in 0.1 parts by weight
to 5 parts by weight with respect to 100 parts by weight of the
monomer mixture.
The molecular weight modifier is not particularly limited, and
examples thereof may comprise mercaptans such as an a-methylstyrene
dimer, t-dodecyl mercaptan, n-dodecyl mercaptan and octyl
mercaptan; halogenated hydrocarbon such as carbon tetrachloride,
methylene chloride and methylene bromide; sulfur-containing
compounds such as tetraethyldiuram disulfide, dipentamethylene
diuram disulfide and diisopropyl xanthogen disulfide, and the
molecular weight modifier may be used in 0.1 parts by weight to 3
parts by weight with respect to 100 parts by weight of the monomer
mixture.
As the activator, one or more selected from among, although not
limited thereto, sodium hydrosulfite, sodium formaldehyde
sulfoxylate, sodium ethylenediaminetetraacetate, ferrous sulfate,
lactose, dextrose, sodium linoleate and sodium sulfate may be each
introduced in a range of 0.01 parts by weight to 0.15 parts by
weight based on a sum of 100 parts by weight of the monomers in
each step.
The redox catalyst is not particularly limited, and examples
thereof may comprise sodium formaldehyde sulfoxylate, ferrous
sulfate, disodium ethylenediaminetetraacetate, copper sulfate and
the like, and the redox catalyst may be used in 0.01 parts by
weight to 0.1 parts by weight with respect to 100 parts by weight
of the monomer mixture.
In the present disclosure, the monomer mixture may be introduced at
once and polymerized, or the monomer mixture may be introduced in
installments and polymerized step by step. When the monomer mixture
is introduced in installments and polymerized step by step, 60% by
weight to 90% by weight of the whole monomer mixture is introduced
in the first step, and 10% by weight to 40% by weight thereof is
introduced in the second step. The reason for such 2-step
polymerization is that processing aid characteristics, surface
characteristics and the like may be improved, and best properties
are exhibited. In addition, an effect of significantly reducing a
non-melting phenomenon may be obtained since solid melting is
smooth.
Next, a core-shell-structured acrylic processing aid is prepared
including preparing a shell by mixing methyl methacrylate, a C12 to
C18 alkyl methacrylate monomer and an aromatic vinyl monomer to the
core and polymerizing the result.
Herein, the emulsion polymerization for preparing a shell is
carried out in the same manner as described above.
After preparing the core-shell, a processing aid in a powder state
may be obtained after going through flocculation.
The flocculation is carried out through adding a flocculant, and
herein, the flocculant may comprise metal halides such as barium
chloride, calcium chloride, magnesium chloride, zinc chloride and
aluminum chloride; nitrates such as barium nitrate, calcium nitrate
and zinc nitrate; acetates such as barium acetate, calcium acetate
and zinc acetate; sulfates such as calcium sulfate, magnesium
sulfate and aluminum sulfate. Among these, calcium chloride and
magnesium sulfate are preferred. The flocculation is carried out at
50.degree. C. to 100.degree. C., and 5% by weight or less of the
flocculant based on the total amount of all the salts used in the
flocculation may remain when flocculated.
Subsequently, a processing aid in a powder state may be obtained by
dewatering and drying using common methods after the
flocculation.
Herein, washing may be carried out at 50.degree. C. to 90.degree.
C. through the use of distilled water and the like, and the acrylic
processing aid prepared after going through such steps has a weight
average molecular weight (MW) of 2,000,000 g/mol to 5,000,000 g/mol
to smoothly perform a function as a processing aid.
Vinyl Chloride Resin Composition
The acrylic processing aid according to the present disclosure is
obtained in a powder state and may be used in forming process of a
vinyl chloride resin.
Such an acrylic processing aid is used as a processing aid when
forming a vinyl chloride resin, and by increasing adhesion
resistance and heat stability of the vinyl chloride resin for
metals without decreasing transparency, resolves a problem of
carbonization that used to occur due to adhesion to a metal mold.
Moreover, surface defects such as air marks, flow marks and fish
eyes having various shapes appearing on the surface either do not
occur or are suppressed to the maximum as well as resolving the
above-mentioned problems during calender forming for sheet
processing of the vinyl chloride resin.
Specifically, the acrylic processing aid according to the present
disclosure is added in 0.1 parts by weight to 10 parts by weight
and preferably in 0.5 parts by weight to 7 parts by weight with
respect to 100 parts by weight of the vinyl chloride resin to be
used in the manufacture of various vinyl chloride resin formed
articles. When the content of the acrylic processing aid is less
than the above-mentioned range, processability, formability and
heat stability obtained from the use of the processing aid are low
declining qualities of manufactured formed articles, and when the
content is greater than the above-mentioned range, processability
declines, and various mechanical and chemical properties decline as
well, and therefore, the acrylic processing aid is properly used in
the above-mentioned range.
Herein, various additives commonly used in the art may be further
included. As the additives, common additives such as a heat
stabilizer, a lubricant, an impact modifier, a plasticizer, a UV
stabilizer, a flame retardant, a colorant, a filler, an
antimicrobial, a releasing agent, an anti-oxidant, a
photostabilizer, a compatibilizer, a dye, an inorganic additive, a
surfactant, a nucleating agent, a coupling agent, an admixture, a
stabilizer, an antistatic agent, a pigment and a resisting agent,
and these may be used either alone or as a mixture of two or more
types.
Calender forming using the vinyl chloride resin composition is not
particularly limited in the present disclosure, and follows known
methods.
Hereinafter, preferred examples are provided for illuminating the
present disclosure, however, the following examples are for
illustrative purposes only, and it is obvious to those skilled in
the art that various modifications and changes may be made within
the scope and technological ideas of the present disclosure, and
such modifications and changes also belong to the scope of the
attached claims.
Example 1: Preparation of Acrylic Processing Aid and Vinyl Chloride
Resin
(Step 1: Preparation of Acrylic-Silicone Block Copolymer Core)
First, a 4-neck flask reactor equipped with a stirrer, a
thermostat, a nitrogen entrance and a circulating condenser was
prepared, 80 parts by weight of deionized water (DDI water), 0.001
parts by weight of ferrous sulfate and 0.02 parts by weight of
disodium ethylenediaminetetraacetate were introduced thereto, and
the temperature inside the reactor was maintained at 70.degree. C.
under nitrogen atmosphere.
As for preparing monomer pre-emulsion, 50 parts by weight of
deionized water, 0.40 parts by weight of an emulsifier (sodium
dodecylbenzene sulfonate; SDBS), 65 parts by weight of methyl
methacrylate (MMA), 5 parts by weight of a silicone-azo
macroinitiator (Mw 10000; SAM) and 0.02 parts by weight of a
molecular weight modifier (tert-dodecyl mercaptan; TDDM) were
introduced to prepare monomer pre-emulsion.
When the temperature inside the reactor reached 70.degree. C., 0.10
parts by weight of potassium peroxide (KPS) and 0.10 parts by
weight of sodium formaldehyde sulfoxylate (SFS) were introduced at
the same time as an initiator over 3 hours together with the
monomer pre-emulsion to progress a reaction.
After 30 minutes from the completion of the monomer pre-emulsion
introduction, 0.01 parts by weight of KPS and 0.01 parts by weight
of SFS were additionally introduced, and the result was matured for
1 hour.
(Step 2: Preparation of Processing Aid Cell)
For cell polymerization, the reactor temperature was maintained at
70.degree. C. Before a reaction, monomer pre-emulsion was prepared
in advance by introducing 30 parts by weight of ion exchange water,
20 parts by weight of DBSO, 15 parts by weight of MMA, 10 parts by
weight of stearyl methacrylate (SMA), 5 parts by weight of styrene
(SM) and 0.01 parts by weight of a molecular weight modifier
(tert-dodecyl mercaptan; TDDM).
The prepared monomer pre-emulsion and, as an initiator, 0.05 parts
by weight of KPS and 0.05 parts by weight of SFS were introduced to
a reactor for 1 hour to progress a reaction.
After 30 minutes from the completion of the monomer pre-emulsion
introduction, 0.01 parts by weight of KPS and 0.01 parts by weight
of SFS were additionally introduced, and the result was matured for
1 hour. The total solid content (TSC) of the prepared latex was
approximately 38% and the latex particle diameter was measured as
130 nm.
For the solid in the polymer latex, 4 parts by weight of a calcium
chloride solution (10% by weight) was introduced at once to
flocculate and obtain slurry, and then the slurry was washed 2 to 3
times with ion exchange water to wash away byproducts, and after a
large quantity of the washing water was removed through filtration,
the result was dried for 3 hours at 70.degree. C. using a small
fluidized-bed dryer used for laboratory use to obtain acrylic
processing aid powder.
(Step 3: Preparation of Vinyl Chloride Resin)
100 parts by weight of a vinyl chloride resin (LS080, LG Chem.
Ltd.) having a degree of polymerization of 800, 1.5 parts by weight
of OT700R (manufactured by Songwon Industrial Co., Ltd.) as a
complex stabilizer, 0.8 parts by weight of G-16 (Loxiol) as an
internal activator, 0.5 parts by weight of G70S (Loxiol) as an
external activator, and 0.3 parts by weight of BMP25 (manufactured
by Pungkyung Fine Chemical Co., Ltd.) as a colorant were mixed in a
Henschel mixer up to 100.degree. C., and 2 parts by weight of the
processing aid prepared above was added thereto to prepare a vinyl
chloride resin.
Example 2: Preparation of Acrylic Processing Aid and Vinyl Chloride
Resin
An acrylic processing aid and a vinyl chloride resin were prepared
in the same manner as in Example 1 except that 8 parts by weight of
a silicone-azo macroinitiator was used in the Step 1 core
preparation, and 20 parts by weight of MMA and 10 parts by weight
of cetyl methacrylate were used in the Step 2 preparation.
Example 3: Preparation of Acrylic Processing Aid and Vinyl Chloride
Resin
An acrylic processing aid and a vinyl chloride resin were prepared
in the same manner as in Example 1 except that the polymerization
temperature was 75.degree. C. in the Step 1 and Step 2
preparations.
Example 4: Preparation of Acrylic Processing Aid and Vinyl Chloride
Resin
An acrylic processing aid and a vinyl chloride resin were prepared
in the same manner as in Example 1 except that the core was
prepared using 60 parts by weight of MMA, 5 parts by weight of BA
and 5 parts by weight of a silicone-azo macroinitiator in the Step
1 core preparation.
Example 5: Preparation of Acrylic Processing Aid and Vinyl Chloride
Resin
An acrylic processing aid and a vinyl chloride resin were prepared
in the same manner as in Example 1 except that the polymerization
was carried out at 63.degree. C. in the Step 1 and Step 2
preparations.
Comparative Example 1: Preparation of Acrylic Processing Aid and
Vinyl Chloride Resin
An acrylic processing aid and a vinyl chloride resin were prepared
in the same manner as in Example 1 except that a silicone-azo
macroinitiator was not used in the Step 1 core preparation.
Comparative Example 2: Preparation of Acrylic Processing Aid and
Vinyl Chloride Resin
An acrylic processing aid and a vinyl chloride resin were prepared
in the same manner as in Example 1 except that 50 parts by weight
of MMA and 20 parts by weight of a silicone-azo macroinitiator were
used in the Step 1 core preparation.
Comparative Example 3: Preparation of Acrylic Processing Aid and
Vinyl Chloride Resin
An acrylic processing aid and a vinyl chloride resin were prepared
in the same manner as in Example 1 except that 0.15 parts by weight
of TDDM was used, and the polymerization was carried out at
85.degree. C. in the Step 1 core preparation.
Comparative Example 4: Preparation of Acrylic Processing Aid and
Vinyl Chloride Resin
An acrylic processing aid and a vinyl chloride resin were prepared
in the same manner as in Example 1 except that the TDDM was not
used, and the polymerization was carried out at 55.degree. C. in
the Step 1 core preparation.
Comparative Example 5: Preparation of Acrylic Processing Aid and
Vinyl Chloride Resin
An acrylic processing aid and a vinyl chloride resin were prepared
in the same manner as in Example 1 except that 25 parts by weight
of MMA and 5 parts by weight SM were used in the Step 2 shell
preparation.
Test Example 1: Measurements on Properties of Acrylic Processing
Aid and Vinyl Chloride Resin
Properties of the acrylic processing aids and the vinyl chloride
resins prepared in the examples and the comparative examples were
measured as follows, and the obtained results are shown in Table
1.
(1) Specific Viscosity (.eta.sp) Measurement
0.5 g of the acrylic processing aid was dissolved in 10 ml of a
tetrahydrofuran (THF) solvent, and specific viscosity was measured
based on the following Mathematical Formula 1 using a Ubbelohde
viscometer. Specific viscosity=(time solution-time THF)/time THF
[Mathematical Formula 1]
(2) Adhesion Resistance Evaluation
For adhesion evaluation, 100 parts by weight of polyvinyl chloride
(degree of polymerization=800, LS080 manufactured by LG Chem.
Ltd.), 3.0 g of a tin-based stabilizer, 0.9 g calcium stearate
(Ca-St) were introduced to a Henshel Mixer at room temperature, and
then the result was mixed at 1,000 rpm while raising the
temperature up to 115.degree. C., and then cooled to 40.degree. C.
to complete a master batch. 3 g of the sample was added thereto,
and after mixing the result again at room temperature, 100 g of the
powder mixture was milled for 4 minutes under the condition of roll
mixing temperature of 200.degree. C., roll revolution count of
14.times.15 rpm and roll spacing of 0.3 mm using a 6 inch 2-roll
mill, and adhesion on the roll surface was evaluated.
A 5-point method was used for the evaluation, and the evaluation
was performed based on the following criteria.
<Evaluation Criteria>
5: Not Stretched at all while being stripped.
4: Hardly Stretched while being stripped.
3: Stretched a little while being stripped.
2: Stripped but stretched much.
1: Not stripped.
(3) Heat Stability Evaluation
To the master batch prepared above, samples to measure were added
in 20 parts by weight each, and after mixing the result again at
room temperature, 100 parts by weight of the powder mixture was
milled for 10 minutes under the condition of roll mixing
temperature of 200.degree. C., roll revolution count of 14.times.15
rpm and roll spacing of 0.3 mm using a 6 inch 2-roll mill, and heat
stability for the sheet samples was evaluated. .DELTA.YI=YI(sheet
sample processed for 10 minutes)-YI(sheet sample processed for 3
minutes) [Mathematical Formula 2]
.DELTA.YI: yellowness index (YI) was measured in accordance with
the ASTM E313-1996 rule using a spectrophotometer (CM-3600d,
KONICA-MINOLTA, INC.). .DELTA.YI means a change in the YI value
after 1000 hours compared to the beginning.
(4) Transparency
To the master batch prepared above, samples to measure were added
in 2 parts by weight each, and after mixing the result again at
room temperature, 100 parts by weight of the powder mixture was
milled for 5 minutes under the condition of roll mixing temperature
of 195.degree. C., roll revolution count of 14.times.15 rpm and
roll spacing of 0.3 mm using a 6 inch 2-roll mill, and transparency
and haze were measured for each of the sheet samples.
(5) Air Mark Evaluation
To the master batch prepared above, samples to measure were added
in 2 parts by weight each, and after mixing the result again at
room temperature, 100 parts by weight of the powder mixture was
milled for 3 minutes under the condition of roll mixing temperature
of 185.degree. C., roll revolution count of 14.times.15 rpm and
roll spacing of 0.3 mm using a 6 inch 2-roll mill, and the sheet
samples were evaluated based on the following criteria.
<Evaluation Criteria>
5: There were no air marks at all.
4: A small number of air marks were observed.
3: Air marks were observed but not enough to become a problem.
2: Air marks were observed and it becomes a problem in the actual
use.
1: Air marks were very much produced and it is not able to be
actually used.
(6) Flow Mark Evaluation
To the master batch prepared above, samples to measure were added
in 2 parts by weight each, and after mixing the result again at
room temperature, 100 parts by weight of the powder mixture was
milled for 3 minutes under the condition of roll mixing temperature
of 200.degree. C., roll revolution count of 14.times.15 rpm and
roll spacing of 0.3 mm using a 6 inch 2-roll mill, and the sheet
samples were evaluated based on the following criteria.
<Evaluation Criteria>
5: There were no flow marks at all.
4: A small number of flow marks were observed.
3: Flow marks were observed but not enough to become a problem.
2: Flow marks were observed and it becomes a problem in the actual
use.
1: Flow marks were very much produced and it is not able to be
actually used.
(7) Fish Eye (Non-Dispersed Melt Projection) Measurement
After preparing a vinyl chloride resin composition without adding a
filler, the composition was extruded to a film having a thickness
of 0.2 mm using a T-die-equipped 20 mm single screw extruder at a
cylinder temperature of 180.degree. C. and a screw rate of 30 rpm,
and the number of fish eyes present in the fixed region on the film
surface was observed with the eye. The evaluation was performed
based on the following criteria.
<Evaluation Criteria>
5 points: When there are almost no fish eyes
3 points: When fish eyes are produced a little
1 point: When fish eyes are much produced
TABLE-US-00001 TABLE 1 Composition (Parts by Weight) Example
Comparative Example 1 2 3 4 5 1 2 3 4 5 Core MMA 65 62 65 60 65 70
50 65 65 65 BA 5 SAM 5 8 5 5 5 20 5 5 5 Shell MMA 15 20 15 15 15 15
15 15 15 25 CMA 10 SMA 10 10 10 10 10 10 10 10 SM 5 5 5 5 5 5 5 5 5
Specific Core 1.1 0.8 0.7 1.2 1.7 1.2 1.3 0.1 2.5 1.0 Viscosity
Acrylic 1.5 1.4 1.2 1.4 1.8 1.6 1.5 0.7 1.4 1.6 [0.3 to 2.0]
Processing Aid Adhesion Resistance 5 5 4 5 5 1 4 3 3 3 [4 to 5]
Heat Stability, 15 13 17 18 14 45 25 35 36 40 .DELTA.YI [10 to 30]
Transparency % 86 85 87 85 87 86 80 86 85 85 [83 to 88] %, [4 to 8]
5.9 6.1 5.7 5.8 5.9 5.4 8.9 5.5 5.6 5.8 Air Marks [4 to 5] 5 5 4 4
5 3 2 1 3 3 Flow Marks [4 to 5] 5 5 5 5 5 3 3 3 1 3 Fish Eyes [4 to
5] 5 4 5 5 5 3 3 2 3 1
According to Table 1, it was seen that the compositions of Examples
1 to 5 using the silicone-azo macroinitiator by the present
disclosure had excellent adhesion resistance and heat stability
while maintaining transparency of 85%, and surface defects such as
air marks, flow marks and fish eyes hardly occurred.
In comparison, it was seen that heat stability and adhesion
resistance were low to a serious level when the silicone-azo
macroinitiator was not used as in Comparative Example 1. In
addition, surface defects such as air marks, flow marks and fish
eyes seriously occurred.
When using the silicone-azo macroinitiator in excess as in
Comparative Example 2, heat stability and adhesion resistance were
somewhat enhanced, however, there was a problem of transparency
decrease.
In Comparative Examples 3 and 4 having the specific viscosity of
the core and the processing aid outside the range of 0.3 to 2.0
while maintaining the silicone-azo macroinitiator content,
transparency was favorable, however, the values were low in terms
of adhesion resistance and heat stability producing various surface
defects.
In addition, in the composition that did not use C12 to C18
methacrylate in the shell as in Comparative Example 5, there was a
problem of serious fish eye degradation.
Through such results, it was seen that, when specific viscosity is
controlled while using a silicone-azo macroinitiator in a core as
an acrylic processing aid and using C12 to C18 methacrylate in a
shell when processing a vinyl chloride resin, transparency was
maintained while securing adhesion resistance and heat stability of
the vinyl chloride resin to an excellent level, and surface defects
were suppressed.
The acrylic processing aid according to the present disclosure is
used in a forming process of a vinyl chloride resin, and increases
adhesion resistance and heat stability without decreasing
transparency and thereby improves forming qualities by improving an
adhesion property for metals.
In addition, processing of high-quality formed article can be
obtained by suppressing the occurrences of air marks, flow marks
and fish eyes that used to occur during existing calender forming
processes of a vinyl chloride resin.
The acrylic processing aid of the present disclosure is used as a
processing aid when manufacturing various formed articles using a
vinyl chloride resin, and facilitates manufacture of formed
articles having excellent properties.
* * * * *